About certain instanced areas... (Rising Stones, Waking Sands, ect.)

[Felis]

Now, I do remember the days at launch when the Waking Sands was not at all instanced, and there were 20+ people crowded in front of Minfilia's desk at any given time. I remember, and I totally understand why they made it instanced. That was a mess lmao.

It was always instanced. What instance you enter depend on where in the MSQ you are.

honestly, they should have made JUST Minfillia's office instanced, and kept the rest of the area public. It makes sense that people wouldn't be running in and out of the Antecedent's office and bugging her constantly, but at least early on, the Scions had a lot more going on than whatever quests you were working on at the time, and having other people going about their business in there helped with that atmosphere.

They make it that way so they can change which NPCs stand where in the rooms depending on where in the MSQ the player is (example the walking sand before and after the garleans raid it).
You still meet other players who are around the same MSQ quests as you.

Of course that don't count for Fortemps Manor, because you are the only guest. While in the Scion HQs you are not the only adventurer.